The present invention relates to an electronic jacquard, in particular for controlling warp selection in a weaving loom.
In conventional electromagnetic jacquards, see for example EP 0188074, the jacquard selectively controls raising and lowering of warp yams between upper and lower shed positions.
In EP 0188074 a pair of hooks are connected via a pulley to one or more harness cords which in turn is (are) connected to healds through which the warp yarns pass.
The jacquard is provided with selection devices which selectively operate to capture one or other of a pair of hooks when that hook is at its uppermost position. This action, in co-operation with the pulley, results in the harness cord raising or retaining the heald and warp yarn at the top of the V shaped shed opening on the warp bed on the loom. Not to select/capture the hook results in the heald/warp lowering or remaining at the bottom of the V shaped shed opening.
In other types of jacquard, a single hook is connected to the harness cord such that raising/lowering of the single hook directly results in raising/lowering of the heald.
According to one aspect of the present invention there is provided an electronic jacquard including a plurality of elongate heald hooks movable longitudinally between upper and lower shed positions and a plurality of electrically operable selection devices for co-operation with the heald hooks for selectively retaining the heald hooks at one of said shed positions, each selection device including a latch movable between a latched position and a non-latched position, the latch when at said latched position being capable of latching engagement with the heald hook in order to retain it at said shed position, and an ultrasonic cyclic motor, preferably a piezo-electric motor, drivingly arranged to move the latch from its non-latched position to its latched position.
Preferably the latch is biased to its non-latched position so as to be capable of moving from its latched position to its non-latched position under the influence of said bias.
Preferably the latch is mounted on a support arm which is formed of a resilient material, preferably spring steel, the arm being fixedly mounted at one end to a body of the selection device and carrying said latch at its opposite end.
Preferably the piezo-electric motor is arranged to move an actuator member which engages the support arm, preferably at a location intermediate the ends of the arm, in order to move the latch to its latched position.
Preferably, the hooks are arranged in pairs for raising/lowering a harness pulley, and each selection device preferably includes a pair of latches and a single motor arranged to control movement of both latches to their respective latched positions.
Preferably each latch is arranged to be rotated upon retaining engagement with a hook when at its latch position, biasing mans being provided to resist said rotation.
According to another aspect of the present invention there is provided an electronic jacquard including a plurality of elongate heald hooks movable longitudinally between upper and lower shed positions and a plurality of electrically operable selection devices for co-operation with the heald hooks for selectively retaining the heald hooks at one of said shed positions, each selection device including a latch movable between a latched position and a non-latched position, the latch when at said latched position being capable of latching engagement with the heald hook in order to retain it at said latch position, the latch when at said latched position being movable between a retention position and a release position, biasing means being provided to resiliently bias the latch to its release position, the hook and latch co-operating such that the hook on engagement with the latch causes the latch to move to its retention position against said resilient bias, and an electrically operable actuator for selectively moving the latch to its latched position.
Preferably the actuator is an ultrasonic cyclic motor, preferably a piezoelectric motor.